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Swinging a sword: how microtubules search for their targets.

Pavin N, Tolić-Nørrelykke IM - Syst Synth Biol (2014)

Bottom Line: The cell interior is in constant movement, which is to a large extent determined by microtubules, thin and long filaments that permeate the cytoplasm.To move large objects, microtubules need to connect them to the site of their destination.For example, during cell division, microtubules connect chromosomes with the spindle poles via kinetochores, protein complexes on the chromosomes.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Faculty of Science, University of Zagreb, Bijenička 32, 10000 Zagreb, Croatia.

ABSTRACT
The cell interior is in constant movement, which is to a large extent determined by microtubules, thin and long filaments that permeate the cytoplasm. To move large objects, microtubules need to connect them to the site of their destination. For example, during cell division, microtubules connect chromosomes with the spindle poles via kinetochores, protein complexes on the chromosomes. A general question is how microtubules, while being bound to one structure, find the target that needs to be connected to this structure. Here we review the mechanisms of how microtubules search for kinetochores, with emphasis on the recently discovered microtubule feature to explore space by pivoting around the spindle pole. In addition to accelerating the search for kinetochores, pivoting helps the microtubules to search for cortical anchors, as well as to self-organize into parallel arrays and asters to target specific regions of the cell. Thus, microtubule pivoting constitutes a mechanism by which they locate targets in different cellular contexts.

No MeSH data available.


Microtubule pivoting in various cellular contexts and in vitro. a Pivoting promotes cortical capture of astral microtubules during spindle translocation from the mother to the daughter cell in budding yeast. b Pivoting helps the formation of a parallel array of microtubule bundles in interphase fission yeast cells. c Pivoting helps microtubules to center the microtubule aster in a microfabricated chamber. Green lines represent microtubules; small grayspheres depict the spindle pole bodies in (a), microtubule-organizing centers in (b) and the centrosome in (c); the large gray sphere in (b) is the nucleus. Dashed lines mark different positions of the microtubules as they pivot and explore the space laterally, searching for their targets. (Color figure online)
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Fig2: Microtubule pivoting in various cellular contexts and in vitro. a Pivoting promotes cortical capture of astral microtubules during spindle translocation from the mother to the daughter cell in budding yeast. b Pivoting helps the formation of a parallel array of microtubule bundles in interphase fission yeast cells. c Pivoting helps microtubules to center the microtubule aster in a microfabricated chamber. Green lines represent microtubules; small grayspheres depict the spindle pole bodies in (a), microtubule-organizing centers in (b) and the centrosome in (c); the large gray sphere in (b) is the nucleus. Dashed lines mark different positions of the microtubules as they pivot and explore the space laterally, searching for their targets. (Color figure online)

Mentions: Once the spindle is near the neck, astral microtubules enter the daughter cell. To pull the spindle through the neck, dynein that is on the microtubules needs to be off-loaded to the cortical anchor protein Num1 (Lee et al. 2005). Angular movement of microtubules, driven by myosin V, most likely helps the microtubules to reach a cortical anchor for dynein (Baumgartner 2011). Thus, the angular movement of microtubules promotes not only the orientation of the spindle towards the neck inside the mother cell, but also the cortical capture of microtubules inside the daughter cell (Fig. 2a), to allow for the interaction with cortical anchors, which is needed for dynein to exert force on the microtubule.Fig. 2


Swinging a sword: how microtubules search for their targets.

Pavin N, Tolić-Nørrelykke IM - Syst Synth Biol (2014)

Microtubule pivoting in various cellular contexts and in vitro. a Pivoting promotes cortical capture of astral microtubules during spindle translocation from the mother to the daughter cell in budding yeast. b Pivoting helps the formation of a parallel array of microtubule bundles in interphase fission yeast cells. c Pivoting helps microtubules to center the microtubule aster in a microfabricated chamber. Green lines represent microtubules; small grayspheres depict the spindle pole bodies in (a), microtubule-organizing centers in (b) and the centrosome in (c); the large gray sphere in (b) is the nucleus. Dashed lines mark different positions of the microtubules as they pivot and explore the space laterally, searching for their targets. (Color figure online)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Fig2: Microtubule pivoting in various cellular contexts and in vitro. a Pivoting promotes cortical capture of astral microtubules during spindle translocation from the mother to the daughter cell in budding yeast. b Pivoting helps the formation of a parallel array of microtubule bundles in interphase fission yeast cells. c Pivoting helps microtubules to center the microtubule aster in a microfabricated chamber. Green lines represent microtubules; small grayspheres depict the spindle pole bodies in (a), microtubule-organizing centers in (b) and the centrosome in (c); the large gray sphere in (b) is the nucleus. Dashed lines mark different positions of the microtubules as they pivot and explore the space laterally, searching for their targets. (Color figure online)
Mentions: Once the spindle is near the neck, astral microtubules enter the daughter cell. To pull the spindle through the neck, dynein that is on the microtubules needs to be off-loaded to the cortical anchor protein Num1 (Lee et al. 2005). Angular movement of microtubules, driven by myosin V, most likely helps the microtubules to reach a cortical anchor for dynein (Baumgartner 2011). Thus, the angular movement of microtubules promotes not only the orientation of the spindle towards the neck inside the mother cell, but also the cortical capture of microtubules inside the daughter cell (Fig. 2a), to allow for the interaction with cortical anchors, which is needed for dynein to exert force on the microtubule.Fig. 2

Bottom Line: The cell interior is in constant movement, which is to a large extent determined by microtubules, thin and long filaments that permeate the cytoplasm.To move large objects, microtubules need to connect them to the site of their destination.For example, during cell division, microtubules connect chromosomes with the spindle poles via kinetochores, protein complexes on the chromosomes.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Faculty of Science, University of Zagreb, Bijenička 32, 10000 Zagreb, Croatia.

ABSTRACT
The cell interior is in constant movement, which is to a large extent determined by microtubules, thin and long filaments that permeate the cytoplasm. To move large objects, microtubules need to connect them to the site of their destination. For example, during cell division, microtubules connect chromosomes with the spindle poles via kinetochores, protein complexes on the chromosomes. A general question is how microtubules, while being bound to one structure, find the target that needs to be connected to this structure. Here we review the mechanisms of how microtubules search for kinetochores, with emphasis on the recently discovered microtubule feature to explore space by pivoting around the spindle pole. In addition to accelerating the search for kinetochores, pivoting helps the microtubules to search for cortical anchors, as well as to self-organize into parallel arrays and asters to target specific regions of the cell. Thus, microtubule pivoting constitutes a mechanism by which they locate targets in different cellular contexts.

No MeSH data available.